Micronucleus induction and phagocytosis in mammalian cells treated with diesel emission particles

Micronucleus induction and phagocytosis in V79 and CHO cells treated with diesel emission particles (DEP) were studied. After separation of the sample into supernatant and sediment fractions, the genotoxic activity of DEP was shown to reside in the supernatant fraction for the DMSO-extracted sample, and in the sedimented fraction for the dipalmitoyl lecithin (DPL), a primary component of pulmonary surfactant, dispersed sample. More particles from DMSO sediment samples were phagocytized than DPL sediment by both types of cells. This had no effect, however, on micronucleus induction. CHO cells phagocytized fewer particles, but gave a higher number of micronuclei than V79 cells. CHO cells seem to be more sensitive to DEP. Evidently, micronucleus induction is not the result of phagocytosis per se, but is due to the different response of the indicator cells to the DEP sample tested. These results further indicate that most, if not all, genotoxic compounds associated with DEP can be extracted by DMSO and that genotoxic activity associated with DEP inhaled into the lung may also be expressed by dispersion of particles in pulmonary surfactant.